Fig. 6.

Changes in gas exchange parameters in tobacco plants under progressing soil water deficits and at re-watering. Plants were exposed to a water deficit for 1 month (irrigated once a week). Gas exchange measurements were performed from 1 to 5 days after the last irrigation date (left arrow) and at the re-watering date (right arrow). a Soil water content was estimated relative to pot weight at the first day from the last irrigation, b photosynthesis rate, c stomatal conductance, and d intrinsic water use efficiency, which is the ratio of the photosynthesis rate to stomatal conductance (A/g _s). Values are mean ± SE from five different plants (n = 5). Statistical analysis was done using an unpaired t test. Asterisks above bars indicate that the means of transgenic plants are significantly different from the SR line on the same day (p < 0.05)